The present invention relates to an air-mix door control apparatus of an air conditioner for automobile and, more particularly, to an air-mix door control apparatus of an air conditioner for automobile which controls the opening of an air-mix door by driving of a motor.
In, for example, Japanese Utility Model Laid-Open No. 108910/1983 a motor driving type air-mix door control apparatus is proposed, in which a power source voltage of a motor is set to a higher level at both end portions of a rotating angle of an output shaft of a motor actuator, in the vicinity of a maximum cooling position and a maximum warming position of an air-mix door, than at an intermediate portion of the rotating angle of the output shaft of the motor actuator in order to improve the air tightness at the both end portions of opening of the air-mix door.
However, the change ratio of a discharge air temperature with respect to the change of opening of the air-mix door is so great near both the maximum cooling position and the maximum warming position that control of the air-mix door becomes unstable in these ranges and further changing of the opening of the air-mix door is likely to occur in these ranges.
If a setting is made in such a manner so as to minimize the change ratio of the discharge air temperature with respect to the change of opening of the air-mix door, the moving driving speed of the air-mix door would drop at the intermediate position of the opening of the air-mix door and the effectiveness of the air-mix door of the discharge air temperature to the set air temperature would drop.
An object of the present invention is provide to an air-mix door control apparatus of an air conditioner for automobile wherein a change ratio of a discharge air temperature with respect to a change of opening of an air-mix door throughout the entire opening range of the air-mix door is constant.
Another object of the present invention resides in providing an air-mix door control apparatus of an air conditioner for automobile wherein a control of an air-mix door control motor in a range in which a change of actual discharge air temperature is drastic with respect to a change of an actual opening of an air-mix door is stabilized.
A further object of the present invention resides in providing an air-mix door control apparatus of an air conditioner for automobile with a high effectiveness of an air-mix door control motor in range in which a change of an actual discharge air temperature is gentle with respect to a change of an actual opening of an air-mix door can be attained.
In order to accomplish the objects described above, the present invention provides an air-mix door control apparatus of an air conditioner for automobile having speed correction means for correcting the rotational speed of an air-mix door control motor in accordance with the control state or the control condition of an air-mix door.
In accordance with the present invention the opening range of the air-mix door is divided into a plurality of ranges on the basis of the relationship between the change ratio of opening of the air-mix door and the change ratio of the discharge air temperature, with a suitable motor speed being set for each of the divided ranges, and with the rotational speed of an air-mix door control motor for driving the air-mix door being changed in each range.
According to the present invention, the rotation speed of the motor for driving the air-mix door control apparatus of the air conditioner for an automobile is controlled and changed over in accordance with the change ratio of the blow-out air temperature with respect to the change of opening of the air-mix door.
Accordingly, the present invention can improve the control stability of the air-mix door control apparatus of the air conditioner for automobile and the responsibility of the air-mix door of the blow-out air temperature to the set air temperature.